Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Qual mulher estava na dupla mista de Tontowi Ahmad e Lilyana Natsir em 2011?
 ###Tabelas: CREATE TABLE season_effects (season_effects_id AUTO_INCREMENT PRIMARY KEY, Storm name VARCHAR, Dates active VARCHAR, Max 1-min wind mph (km/h) VARCHAR, Min. press. ( mbar ) VARCHAR, Damage (millions USD ) VARCHAR, Deaths VARCHAR) CREATE TABLE planned_for_theatrical_release_but_never_screened_theatrically (planned_for_theatrical_release_but_never_screened_theatrically_id AUTO_INCREMENT PRIMARY KEY, Title VARCHAR, Series VARCHAR, Director VARCHAR, Characters VARCHAR, Release date VARCHAR) CREATE TABLE previous_winners (previous_winners_id AUTO_INCREMENT PRIMARY KEY, Year INT, Men's singles VARCHAR, Women's singles VARCHAR, Men's doubles VARCHAR, Women's doubles VARCHAR, Mixed doubles VARCHAR) CREATE TABLE homologs (homologs_id AUTO_INCREMENT PRIMARY KEY, Species VARCHAR, Species common name VARCHAR, NCBI Accession Number (mRNA/Protein) VARCHAR, Length (bp/aa) VARCHAR, Protein Identity VARCHAR) CREATE TABLE weekly (weekly_id AUTO_INCREMENT PRIMARY KEY, Episode VARCHAR, Air Date VARCHAR, Timeslot VARCHAR, Households (Rating/Share) VARCHAR, 18-49 (Rating/Share) VARCHAR, Viewers (m) INT, Weekly Rank (#) VARCHAR)  
SELECT Women's singles FROM previous_winners WHERE Mixed doubles = tontowi ahmad lilyana natsir AND Year = 2011